This invention relates to filters for use in chemical processes and in particular to the methods of cleaning filters used for filtering dope in a solvent spun fibre manufacturing process, and to apparatus for cleaning such filters.
In the manufacture of solvent spun fibres such as, for example, Tencel (Trade Mark of Courtaulds Fibres Limited) cellulose fibre, a dope comprising woodpulp dissolved in an aqueous solution of amine oxide, is pumped under pressure through a series of filters to a plurality of spinnerette heads. The jets of each spinnerette head are typically 80 microns or less. Therefore the filtration of the dope is extremely important in order to avoid blockages of any of the spinnerette jets.
Modern plants, such as that installed by Courtaulds Fibers Inc at Mobile, Ala., USA are designed to produce many hundreds of tonnes of fibre on a continuous basis. The flow of dope to the spinnerette jets cannot be disrupted or varied at all without disastrous consequences. It is therefore extremely important that meticulously clean filter are used and that the process for cleaning the filters is as thorough as possible.
An object of the present invention is to provide a method of cleaning filters of a solvent-spun fibre manufacturing plant thoroughly and apparatus for carrying out the method.